1. Technical Field
The present disclosure relates to illuminating devices, particularly, to an acoustic illuminating device.
2. Description of Related Art
An illuminating device generally includes a light source, a holding structure to hold the light source, and a lampshade to cover the light source. However, in many applications, people may need or want the illuminating device to emit sound as well as light. To solve this problem, an additional acoustic member can be mounted on the holding structure.
There are different types of acoustic members that can be categorized according by their working principles, such as electro-dynamic acoustic members, electromagnetic acoustic members, electrostatic acoustic members and piezoelectric acoustic members. The various types ultimately use mechanical vibration to produce sound waves, in other words they all achieve “electro-mechanical-acoustic” conversion. Among the various types, the electro-dynamic acoustic members are most widely used. For example, an electro-dynamic acoustic member, according to the prior art, typically includes a voice coil, a magnet and a cone. The voice coil is an electrical conductor, and is placed in the magnetic field of the magnet. By applying an electrical current to the voice coil, a mechanical vibration of the cone is produced due to the interaction between the electromagnetic field produced by the voice coil and the magnetic field of the magnets, thus producing sound waves by kinetically pushing the air. The cone will reproduce the sound pressure waves, corresponding to the original input signal.
However, the structure of the electro-dynamic acoustic member is dependent on magnetic fields and often weighty magnets. The structure of the electric-dynamic acoustic member is complicated and enlarges the size of the illuminating device. The magnet of the electric-dynamic acoustic member may interfere or even destroy other electrical devices near the acoustic member.
Further, in other situations, people may need the illuminating device to emit heat as well as light. To solve this problem, a high-power bulb can be used as the light source in the illuminating device, and thus the choice of the light source is limited.
What is needed, therefore, is to provide an effective illuminating device having a simple lightweight structure that is able to produce sound and heat, as well as light.